Process for simultaneous recovery and cracking/upgrading of oil from solids

ABSTRACT

The present invention relates to a process for the simultaneous recovery and cracking/upgrading of oil from solids such as tar sand and oil shale. With this process a number of the obstacles with the existing technology are solved, and the process upgrades the oil into a lighter product than the existing technology, remove sulphur in the order of 40% and heavy metals in the order of 90%.

FIELD OF THE INVENTION

The present invention is related to a process for recovery of oil fromtar sand (also called oil sands) and/or oil shale and upgrading the oilin the same process.

BACKGROUND

Tar sand is found in enormous quantities in a number of countries, thegreatest resources are found in Canada and consist of heavy oil and sandin natural resources in different depths. These resources have been thesubject of intensive research in an effort to develop technologies forrecovery of the oil from the sand. Thus, a number of differenttechnologies exist.

Alberta's most important mineral resources are oil and natural gas, andthey account for about 90 percent of Alberta's income from mining.Alberta produces approximately two-thirds of Canada's oil and more thanthree-quarters of its natural gas. Nearly half of Alberta's oil is minedfrom vast oil sands, which are deposits of a heavy crude oil calledbitumen. Alberta's oil sands represent the largest known deposits ofbitumen in the world. The oil sands occur in three major areas of theprovince: the Athabasca River Valley in the northeast, the Peace Riverarea in the north, and the Cold Lake region in east central Alberta.Bitumen is more costly to mine than conventional crude oil, which flowsnaturally or is pumped from the ground. This is because the thick blackoil must be separated from the surrounding sand and water to produce acrude oil that can be further refined.

During the 1950s and 1960s, oil deposits were discovered in otherregions, such as the Peace River area and the Swan Hills, south ofLesser Slave Lake. By the late 1960s the last major oil deposits hadbeen found.

The bitumen, which contrary to normal crude found in deep reservoir,does not have the same light fractions as these, have been evaporatedoff over thousands of years. The bitumen thus consists of heavymolecules with a density exceeding 1.000 kg/dm³ (less than 10 API) and aviscosity 1000 times higher than light crude. In addition the tar sandcontains sulphur over 4% by weight and hundreds of ppm with heavymetals. The content of organic matter in tar-sand can range from 5% byweight up to 20% by weight, and thus extraction of oil from tar sandinvolves huge mass transport.

Because of the composition of the bitumen, it has to be upgraded beforeit can be refined in a refiner as light crude.

Because of the economical potential of these huge resources, a number ofdifferent processes exist for the recovery of oil from tar sand. Suchtechnologies involve biological, solvent, thermal and processes wherethe oil is washed out of the sand by superheated water.

Because of the enormous amounts of sand (tailings) associated with tarsand extraction, the different processes face a number of environmentalconstrains.

Contrary to tar sand, oil shale is shale containing organic matter knownas keorgens which can not be washed or dissolved as for the bitumen intar sand. To recover oil from oil shale, it must be heated to atemperature of 500-600 C whereby the organic matter is cracked intoliquid products. As for tar sand, oil shale contains a number ofunwanted constituents, which cause environmental constrains. And as fortechnologies for recovering oil from tar sand, there exist a number ofdifferent technologies for recovering oil from oil shale.

SUMMARY

The present invention is related to an energy self sustained processwhere a number of the obstacles with the existing technologies aresolved, and which in addition to the oil recovery, upgrades the oil intoa lighter product than any other existing technologies, remove sulphurin the order of 40% and heavy metals in the order of 90%. In additionthe process disposes of tailings with limited environmental constraintsas the inorganic matter (sand) is disposed of in dry condition.

The process is a rapid “dry-wet” fluidised process where the sand ismixed into a fluidised reactor fuelled with part of the organiccomponents in the tar sand. The combustion gases strip off the oil fromthe sand, together they act as a pneumatic carrier transporting sand andits associated gases to a cyclone reactor where the sand is separatedfrom the gas stream, which then is routed to a condenser system. Aportion of the condensed oil can be routed back into the stream via anatomisation nozzle for a second cracking whereby the process recoversand upgrades the oil in one operation without the need for upgradingunits.

To optimise collisions between the particles in order to obtain maximumshear forces between the solids the stream of sand, combustion gassesand hydrocarbon gasses are accelerated and retarded in a riser ofvarying diameter.

The collisions between the particles give rise to a mild hydrogenationof the oil by sonoluminiscence of microscopic steam bubbles trappedbetween the colliding solid particles. When steam bubbles are trappedbetween unevenness in the tumbling particles, the steam is subject to anadiabatic compression whereby the temperature and pressure in thebubbles is raised several thousand times above overall temperature andpressure in the process. This causes water to enter into a supercriticalstate where water is cracked into hydrogen and hydroxyl radicals.Hydrogen, which is absorbed by the heavy oil chains, reduces theirbonding whereby the impact forces from the tumbling grains can crack themolecules and the “explosion” of the microscopic steam bubbles takesplace. The majority of the hydrogen is then released and react back withthe hydroxyl radicals into water, but a part of the hydrogen causes amild hydrogenation of the product.

It is highly desirable to achieve good sand/oil mixing as early and asquickly as possible. The method described to achieve this requires theabove-mentioned acceleration and retardation of the stream.Traditionally, steam is the medium used to maintain solid bed fluidityand movement in the riser. Steam, however, has a deleterious effect onthe very hot solids that is met in residue cracking processes. Underthese conditions steam causes hydrothermal deactivation of the catalystin for example FCC-crackers.

This is overcome by the present invention by using the off gasses fromthe fluidised bed reactor regenerator (CO/CO2 and hydrocarbon gasses) asthe carrier of the solids, which will act as a catalyst in cracking ofthe oil.

To have the process verified, a 2.5×2.5×3 m test rig was built andlocated at SINTEF ENERGY RESEARCH AS in Trondheim, Norway with a maximumpower of 125 kW.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram of the process described herein;

FIG. 2 shows an alternate 10 bbl/day plant;

FIG. 3 shows a rig layout;

FIG. 4 shows the rig during testing; and

FIG. 5 shows oil sand, recovered oil, and clean sand from the test.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The lay-out of the rig is shown in FIG. 3.

FIG. 4 shows the rig during testing.

The energy requirement to process one kg of oil sand is given by:

Q=x _(s) *c _(s) *dt+x _(o)(c _(s) *dt+r _(o))+x _(w) *H

Where:

x_(s)=weight part sand (including metals and sulphur), example 80%

x_(o)=weight part oil, example 15%

x_(w)=weight part water, example 5%

c_(s)=specific heat of sand kJ/kgK=1 kJ/kgK

c_(o)=specific heat of oil at operating temperature kJ/kgK=approx 2.25kJ/kgK

r_(o)=heat of evaporation kJ/kg=approx 225 kJ/kg

dt=temperature difference between operating temperature and feedtemperature of sand K

H=enthalpy of water at operating temperature kJ/h=3500 kJ

Operating temperature 360 C=633 K

Feed temperature 90 C=363 K

dt=270 K

Q=516 kJ/kg and which gives a capacity of the test rig of 872 kg/hr sandcontaining 130 kg oil which gives a capacity of approx. 20 bbl/day.

The tests were carried out with tar sand from the Athabasca River Valleydeposits with the properties listed above where the following resultswere obtained:

Density of oil recovered from the fluidiser: 21 API.

Density of oil recovered in the riser: 29.3 API. Density of oil drainedfrom the oil condenser: 25.15 API.

Remaining coke in spent sand 1.25 W %.

Reduction of sulphur in the oil: 45%

Reduction of heavy metals: 87%

Energy consumption in % of recovered oil: 9.3=approx. 12.5 kgoil/hr=approx. USD 3.93 per bbl. (Oil price USD 50 per bbl)

FIG. 5 shows oil sand, recovered oil and clean sand from the test.

The process is described further in the simplified flow diagram in FIG.1.

A) shows the vertical fluidised reactor which have a fluidising mesh B)positioned a distance from the bottom of the vessel. The space betweenthe bottom and the fluidised mesh B) is a plenum C) which receives thecombustion gasses from a combustor D) which can be fuelled either by gasand/or recovered oil. The combustion gasses will heat and fluidise thesolids (sand) E) entrained in the reactor A). The pressure from thecombustion gasses built up in the reactor, will cause the solids and theentrained gasses which consists of combustion gasses, steam andhydrocarbon gasses, to be pneumatically transported through a riser JJ)into a reactor cyclone G) which is so designed that, contrary toordinary cyclones, the solids are spinning several hundred times in thecylindrical part of cyclone before falling down the conical part H) andback into the fluidiser. At the bottom of the conical part of thecyclone, superheated steam is injected into the cyclone by the pipe I)to strip off hydrocarbons between the falling solids in the cyclonewhich falls into the reactor A) via a dip-leg.

Oil sand is injected into the reactor A) by a feed system Cc) and Dd).The same amount of sand injected into the reactor A) has to be drainedfrom the reactor. This is done through the pipe arrangement K) where thesand is transported to a fluidising combustor L) where remaining coke isburned off by injection of air through M). The exhaust gasses from L)are passed through a gas cleaning and heat recovery system N) before itis vented to air.

The “clean” solids from L) are routed to a solid/liquid heat exchangerO) which is heating cooling water from the heat exchanger Z) deliveredfrom the water supply pump P). The hot water is further transported to aboiler Q) located in the combustor L). The boiler is producing steamwhere a part of this is routed to a super-heater R) located in theplenum C) of the reactor A). The superheated steam is routed to theinjection nozzle S) for steam atomisation of oil, the dip-leg J) on thereactor cyclone H) and the dip-leg T) on the separation cyclone U). Thecooled “clean” sand can be disposed of from the heat exchanger O) to aland fill as the sand will be dry and free from any volatilehydrocarbons.

Excess steam not being superheated is routed through pipe V) forpreheating of feed, process purposes or for generating electricitythrough a steam turbine system.

From the reactor cyclone G) and the separation cyclone U) the gaseousstream is routed to a condenser W) set to about 95 C whereby the mainpart of the oil gas is condensed into liquid oil. The gas is condensedby the mean of the recovered oil as the oil collected at the bottom ofthe condenser is pumped by the pump X) through a heat exchanger Z) andcooled by water delivered by the pump P). From the heat exchanger Z),the cooled oil is routed to the top of the condenser and condenses theincoming oil gasses. As the level of the oil rises in the condenser, theproduct is drained off through the pipe BB). The non-condensable gassesand steam are routed to a second condenser CC) which is cooled by waterinjected from the pump P). Condensed water is drained off from thecondenser through the pipe DD) and is collected in a settling tank EE).In the settling tank EE), light oil brought over from the oil condenserCC) will be decanted off through the pipe FF) to the product line fromthe oil condenser W) and routed to a receiver via pipe AA). Water isdrained off through the pipe GG) to drain.

Non-condensable in the condenser CC) is exhausted through the pipe HH)either to air or to a gas cleaning system depending on the localemission requirements.

A portion of the product is returned to the riser JJ) through the pipeNN) by a high pressure pump LL) to the atomisation nozzle S) attached tothe riser JJ).

The atomisation nozzle S) receives the steam for the atomisation of theoil from the super heater R).

Excess formed combustion gasses in the reactor which are not needed forthe transport of the sand in the riser JJ), can be vented from thereactor via the pipe OO) into a gas cleaning and heat recovery systemnot shown.

When the reactor is heated to operational temperature by the combustorD), the gas or oil supply for the combustion can gradually be turned offwhereby the injected air will cause an internal combustion of the formedhydrocarbon gasses in the reactor A) whereby the process will be selfsustained by energy extracted from the tar sand itself. Alternativelythe combustor can be fuelled with a part of the recovered oil deliveredby the pump LL).

To obtain the abovementioned acceleration and retardation of the streamin the riser, this can be obtained by giving the riser varyingdiameters. One preferred embodiment is to form a part of the riser as aLaval nozzle where the atomisation nozzle(s) S) is(are) located eitherin the narrowest part of the ejector or where the ejector starts toexpand.

The entire process is a high intensive thermal process with a highenergy density because of the velocity of the gas and sand stream.Because of the velocities in the process, the intensive heat exchangebetween sand and oil and the low partial pressure of the hydrocarbongasses caused by the combustion gasses and steam, the process canoperate at a temperature in the range of 300-500 C. Apart from reducedthermal stress and energy consumption, this low temperature reducespolymerisation of the cracked product.

FIG. 2 shows an illustration of a 10.000 bbl/day plant.

1. A process for simultaneous recovery and cracking/upgrading of oilfrom solids, such as tar sand and oil shale, wherein oil containingsolids are injected into a fluidized bed reactor where the hydrocarbonsare evaporated off and where the heat for the evaporation is deliveredby internal combustion of a part of the hydrocarbons in the solids or byan external combustor, and that the combustion gasses together with theevaporated hydrocarbons act as a pneumatic carrier of the solids andreduce the partial pressure of the hydrocarbon gasses and where thestream is routed to a cyclone reactor and further to a solids removalseparator and further to a condensing system for the condensable gasses.2. A process for simultaneous recovery and cracking/upgrading of oilfrom solids, such as tar sand and oil shale, in accordance to claim 1wherein a portion of the product from the condenser system is routedback to the stream in a riser via a atomization nozzle whereby thestream of solids acts as a cracking medium by shear forces, heatexchange and sono-luminiscence.
 3. A process for simultaneous recoveryand cracking/upgrading of oil from solids, such as tar sand and oilshale, in accordance to claim 1, wherein the riser have differentdiameters so as to obtain acceleration, retardation and optimizedcollisions between the solid particles in the stream.
 4. A process forsimultaneous recovery and cracking/upgrading of oil from solids, such astar sand and oil shale, in accordance to claim 1, wherein thetemperature in the regenerator is controlled by the injected wet oilsand into the regenerator.
 5. A process for simultaneous recovery andcracking/upgrading of oil from solids such as tar sand and oil shale inaccordance to claim 1, wherein the oil stripped sand is routed to afluidized combustor where remaining coke on the sand is burned off byinjection of air into the combustor and where the released heat is usedfor production of steam, and where the exhaust gas from the combustor isalternatively routed to the plenum of the stripping reactor toparticipate with heat and fluidizing gas for stripping of the oiltrapped on the sand.
 6. A process for simultaneous recovery andcracking/upgrading of oil from solids, such as tar sand and oil shale inaccordance with claim 1, wherein a portion of the stripped sand is mixedwith oil sand for heat recovery and homogenizing of the sand improvingthe feed to the reactor.
 7. A process for simultaneous recovery andcracking/upgrading of oil from solids, such as tar sand and oil shale inaccordance with claim 1, wherein the fluidized bed reactor has twodiameters, where the lower part of the regenerator has a smallerdiameter than the upper part in order to reduce the gas velocities inthe upper part of the regenerator.
 8. A process for simultaneousrecovery and cracking/upgrading of oil from solids, such as tar sand andoil shale in accordance with claim 1, wherein stripped sand in theregenerator is continuously discharged from the regenerator via a pipewhich outside of the regenerator has a “water” trap which may be Uformed and where steam or gas is injected into the pipe opposite the“water trap” for pneumatic transport of sand falling into the trap.
 9. Aprocess for simultaneous recovery and cracking/upgrading of oil fromsolids such as tar sand and oil shale in accordance with claim 1,wherein a battery of regenerators are arranged around a joint chargingsystem and a joint sand receiving collector and heat recovery fluidizer(L) and where the off gasses from the regenerator share a joint sandseparation system and a joint condenser set up and where cooledcondensed oil acts as a condensing medium in the oil condenser by directcontact between the hot oil gasses and the cooled condensed oil.